skysight-inc/HackerNews huggingface dataset:
Firstly, I agree that machine learning is effectively parameter search but the name an artefact of history and we both appear to understand what it means so I don't see how this adds to the argument.

Secondly, no, John didn't say learning theory is "useful only in a crude way", he said, "learning theory is most useful in it’s crudest forms". Big difference. And besides, he says right at the beginning of the post that he believes "learning theory has much more substantial applications [than generating papers]".

To be convincing, theory needs to be precise – if you are not careful about what you are talking about it is easy to believe things that are not true. However, what I think John is saying is that value of theory comes from afterwards abstracting away the precision and understanding the main message (i.e., the "crude form") of a theoretical result. In general, I don't think it is possible to get to a convincing "main message" or "crude form" without someone having grappled with the details.

No matter how many experiments you run, you will only ever show that an algorithm works well or not in a typically small finite number of cases. What theory does is look those cases and ask something like, "It seems that every time X is true of my problem, an algorithm with property Y works really well. I wonder if that is always true?" This type of question gets carefully formalised and then (hopefully) answered. The process of formalisation (i.e., defining things carefully) can yield new ways of thinking about things (e.g., over fitting and bias-variance trade-offs), and having an answer to the general question means that you can be assured that future uses of your algorithm will behave as expected.

You seem to have an unshakeable opinion that mathematics/theory/"pencil-pushing" is inherently a waste of time. That's a real shame. Why do you believe the pursuit of precision, insight, and proof are somehow inferior to running experiments? I find both to be valuable and the interplay between the two extremely rewarding.
You'll need this if you want energy-efficiency when solving parallelizable problems. Use one chip in energy-limited systems, like battery-powered robots. Use multiple chips in power/heat-limited systems, like supercomputers.
Which "parameters" are you optimizing? Where did the corresponding model come from?
When is a certain model even applicable? How do you implement the search procedure
efficiently? Is the result actually meaningful? Can you expect future predictions
to make sense or did you overfit to your training data?

To avoid any fluff, let's go with a concrete example: some of the best performing algorithms
for segmentation are based on spectral clustering (http://en.wikipedia.org/wiki/Spectral_clustering).
What does an eigenvector corresponding to the second-smallest eigenvalue of the
normalized graph laplacian have to do with random walks? How do you compute it?
I'm looking forward to starting a whaling company on the moon.
> What the author uses as his strawman is a linear algebra course for engineers.

If that's true, I'm sorry for the engineers who took this course.

I did not see a single number in my algebra course, neither 2d or 3d vectors. As a matter of fact, we followed the same program that math students (axioms, theorems, linear spaces, rings, ...). Even some teachers were teaching in both faculties, and our exams usually were more difficult (this was just a policy, there were too many engineering students).

Now, I'm in a different university where the maths future engineers study are much more "practical". It's sad seeing that students cannot understand, for example, that a principal direction in a stress tensor is just an eigen-value or that a rotation is just a change of base and, therefore, there are many theorems and properties you can apply to these concepts just making use of some basic algebra.

It's always good to know well the tools you have to use and, for an engineer, algebra is one of the most important tools.
'It's not a post-PC world: Just a post Windows one, maybe'
Nice tool for finding best map projection for a given location/zoom level
Very good way of summing it up!
I'm enormously glad that Apple board did absolutely not keep their company asshole-free.

Writing this on computer that asshole created.

And btw, I do not know a single Genius (with uppacase G) who is not an asshole, so go figure...
When I was a kid I adored his Scientific American columns... what a great man, teacher, puzzlemaster, mathemagician. Dr Matrix!
Bayesian is cool because you can make arbitrarily complex models, and when you have the parameters estimated it is really easy to calculate all the cool things you want to.

Bayesian is not cool because estimating the parameters takes bloody ages on a supercomputer, unless you spend ages being really careful to specify your model.

Frequentist statistics is cool because it is a massive big bag of tricks to estimate all sorts of stuff, and pretty much all of the tricks are already in R.

Frequentist statistics is not so cool because calculating all the specific things you want to can be a pain in the ass.

Once either Quantum computers kick in or a better algorithm than MCMC for Bayesian is created, Bayesian will win.

There are some philosophical arguments about the objectivity of the prior in Bayesian statistics, but these wash out in a decision theoretic framework because of the subjectivity of the utility function at the other end of the process.

Also, less than 5% of people reporting p-values really know what a p-value is.
That’s really nice. My only gripe is that I find the definition font really hard to read.
Gimp might be a better source of inspiration for this sort of thing.
> However, of those 48 companies that disappeared. Aren't those essentially liquidity events resulting in a lot of money for the shareholders?

Some were probably good, others bad for the shareholders.
I'm so hoping this gets funded.
Looking at GEGL, which gimp is moving to might be a good way. It's also a nice system that could get something more than photoshop.
The entire collection of the books that collected those columns is available on CD-ROM as PDFs: http://www.amazon.com/Martin-Gardners-Mathematical-Games-Gar...
> acknowledging the subjectivity of their opinions rather than presuming to present an indisputable statement of truth.

I actually try hard to use I wherever possible for that particular reason. Saying "I think a message-passing style would be best for this" is more honest than "a message-passing style would be best for this".
Facebook Could be Working on Synchronous Multiplayer Gameplay
I think folk need to stop abusing the term "supercomputer".

It is not really a performance designation. It doesn't define a certain architecture or design.

It is pretty clearly an economic designation.
> meh, if that gets the job done faster then say it. The chance of a 20 minute argument vs a weeks long delay? I'll take the 20 minute argument.

I think it's possible that you misread my comment. In this scenario you get the 20 minute argument plus the week long delay, at least in my experience.
I'm surprised by how many comments on cpercival's exam series boil down to "I'll never use this!" Especially since this is Hacker News, almost ground zero for intellectual self improvement. I can't claim to remember (or have even learned, in some cases) much of this stuff, but decisions made without any knowledge of e.g. calculus, probability, etc. will be very sub-optimal.
No, that's a good sysadmin. Bad sys admins are indispensable.
http://en.wikipedia.org/wiki/TILE64

Tilera did a very similar looking 64 cores on a chip in 2007, which is the oldest instance I know of off the top of my head. Their devices cost(or at least they used to) a few grand though. Tilera has bumped it up to around 100 per chip these days. I don't know anything about either architecture so it is hard to say if 64 1Ghz adapteva cores compares with 64 1.5Ghz Tilera cores.

So not quite cutting edge just an under explored side channel.
Googles mod_pagespeed for Apache does dynamic resizing of images.
Show Doing Well On BitTorrent? We’ll Buy It, Says Media Giant
:) This is surely just degenerating into parody now. I can't wait for part 4: "Build a Turing Machine from scratch using paper-clips and sticky tape and send it to me for grading. Remember to show your working and no looking it up on Google."
32 MB of heap is not any problem for modern GCs and modern RAM speeds. With a typical DDR3 memory with bandwidth of 16 GB/s that should fully GC in a few ms. And good GCs usually don't stop the mutator in the marking phase (at least so do some GCs in Java), so the total blocking time could be even lower.
So this is all very well and good, I've had about 5 intros to Bayesian Statistics. But those are a fair bit away from actually applying that knowledge in practice in software.

Let's say we have N different kinds of events with unknown probabilities and unknown dependence or independence between them. The naive approach to gathering data on the probability of event n occurring following an occurrence of event m would require O(N²) in space. Let's say N ~ 10⁹~10¹⁰. Storing that much data as a raw matrix isn't practical in most cases, so we have to find a more efficient data structure - in terms of both space and the operations we need to perform. (and taking into account characteristics of the storage medium, i.e. memory or disk or a combination) What happens if the probabilistic properties of the system change over time?

Are there any introductory books or other resources on modeling this kind of problem? Clearly this has been tackled before, but I'm having a hard time making the leap from theory to practice - and I don't mean import the data into R or SPSS or whatever and let that grind out a solution, but coming up with approximations when you have runtime and space constraints that make that approach impractical.
Ted | Trifter
I always wondered why they never made a service for the Wii. To me, it seemed like the perfect device to test out whether console streaming has merit.
Indian railways : more than 5 million employees, I wonder why wikipedia dosen't list it?
> But isn't this getting overboard?

Naive bayes, with a relevant dataset, does a very fine job of data classification(sentiment analysis, spam detection...). Also, almost everyone who isn't a liberal arts major would have come across Bayes theorem in high school or college.

The question about A/B testing is solving simple linear equations. I believe anyone in 10th grade or above should be able to solve it.

Hashing and MAC are pretty much application level security - they don't require intrinsic knowledge of how; what and why is something an application developer should know.

That leaves us with that harmonic progression thingy and padding. Padding, I think, is to avoid cryptanalysis(extrapolating from what you know is a part of knowing things:)).

Overall, I won't say he is going overboard with his questions. If anything, to anyone familiar with the topics, his questions are pretty trivial. The only thing under contention is if the topics he considers relevant are actually relevant.
Registration for FOSS.IN/2012 now open
> And what's the motivation behind the formula for the determinant?

FWIW, that book has two explanations: the first on p 296 is a lot like "that's how it works out" and the second on p 320 is geometric.

> why does the determinant work to solve linear equations (i.e. Cramer's rule)?

Does the explanation on p 331 of joshua.smcvt.edu/linearalgebra/book.pdf help? (It uses the geometric understanding of the determinant.)
Indian railways employs a number of methods. The most primitive fallback is the one where the station master updates the system whenever a train passes the station, whether or not it stops there.
Where would I put my groceries? :)
Indeed this is very dramatic. Positive feedback boosts egos, negative feedback gets the work done. If no one ever received negative feedback, we would spend our lives believing we're perfect while doing everything wrong.
> From then, even games that had been confirmed or greenlighted were pulled if Gaikai got them first.

Maybe these titles had high licensing costs (regardless of whether any OnLive users rented them or not), and they figured if their competitor had the game less people would be playing it with OnLive? So they'd be more likely to make a loss on the licensing cost.
Old news that's still very, very relevant.

I just switched to Verizon from another carrier and didn't know about this. I much appreciated the post.
As hinted at in a comment a few threads down, sometimes the sheer effort of trying to impart some knowledge or technique when other developers clearly don't want to hear it takes its toll.

In those situations, it is a lot less effort to allow developer B to commit whatever the hell they want into the codebase, wait until they lose interest and then go in later and clean up the mess.
Most of the questions are pretty trivial and relevant(may be not to you but that doesn't make it irrelevant or a parody).

http://news.ycombinator.com/item?id=4635946
No, I think there's a valid point. The difference between a mild interest and a passion is precisely how much attention and effort you devote to it.

When I was young, computers at home were quite rare. But once I was exposed to them I was hooked. I rode my bicycle to the Radio Shack and stood at the display model writing programs. I saved and bought a Sinclair ZX-80. Almost all of my free time went into programming.

Then there are all the people I've known that say they want to learn to code. People who grew up with a computer, and went to school were there were programming classes, and work alongside programmers. They think they'd like to learn programming, but really they're not interested enough to bother.
I met some. It was fun to see, how they could communicate with spanish people.
I'd love to know a few of those decisions that you've to take on a day-to-day basis (even once every month) as a software developer, which needs calculus and probability.
This. Give someone a project that should take no more than n hours to complete and give then n/2 days to do it, preferably including a weekend. That should be plenty of time for some folks, even employed.
I am sure "being delayed" had a lot to do with the fond memories :-)

When I was a kid and used to go on vacation with family, the late train was so good for me. It meant few extra vacation hours before schools and homework would start. I hope it would become the same again. BTW, only my lifestyle has changed. Train timings are still there where they were 15 yrs ago or maybe have become "more relaxing" :-)
Also not useful for SEO or a host of other requirements on the web.
World Countries and Time Zones API
Well, they had to do the customer validation :) .

My untested hunch is that there is a good enough market for these services.

I might be a customer too, I'm a former gamer that now has to cope with work, study and very soon a family, having an "instant-on" service would be worth it for me.

And why is it prohibitive for you? It says it used to cost U$ 4.95/month, which I perceive as really cheap (as compared to U$ 50 for a title like Diablo III).

Much like the Nintendo Wii, I don't think that hardcore gamers is the target demographic.

Edit: see sshirkov's comments, I fall in the same demographic I guess.

http://news.ycombinator.com/item?id=4635436
"Why should a message be "padded" (and not just with zeroes) before being encrypted or signed using RSA?" I just happen to know this one. I know effective developers that don't. This is not 'basic' information.

"What is the expected run-time of quicksort? What is the worst-case run-time?" Who cares? Call the sort method on your array class, call a sort function. Done. I don't need to know this for everyday things.

"Name and describe the four states in MESI cache coherence." This is 'basic' knowledge? Maybe if I wrote a kernel in school, and if I did, I certainly don't remember the details of dealing with cache coherence 25 years later. I'm not a kernel developer now. Nor are a Very Large Percentage of developers in the real world.

"Which of the following two functions is faster, and why? Assume that the C code is translated into machine code in the obvious manner, without optimization." Again, I just happen to know this one. But the "without optimization" almost makes the exercise silly. As your employer, I'd want to know you have the analytical skills to find the bottleneck in the code or to discover the compiler bug whose optimization is causing problems.

"Explain the difference between a mutex and a read-write lock." Sorry, I'm using a higher-level construct. GCD from Apple, go routines in go ... do I 'fail' this question because I don't have to remember this from 15 years back?
> Another one of my common things I do at work is replacing quicksort implemented using recursion with an iterative version so that the stack doesn't keep getting blown on large datasets.

What language do you use which doesn't already have an optimized version of quicksort or equivalent?
Firefox 16 released with powerful developer tools
Misleading headline. They didn't suppress snooping, they refused to disclose the plan to snoop. (Which has been in the works since at least 2010 when another such call was denied, says the article.)
Look at the date of Mark Cuban's post (March 18, 2012).

Cal Newport and Mark Cuban are both well known bloggers who have been making this same case for some time. No plagiarism involved.
The bicymple. The bicycle, simplified.
> I'd love to know a few of those decisions that you've to take on a day-to-day basis (even once every month) as a software developer, which needs calculus and probability.

Machine learning needs an understanding of basic statistics and probability.
This is not an one-liner by any means. By this definition the entire linux kernel can probably be compressed into one very long line too.
Video at http://blogs.rsa.com/idp-beat/announcing-rsa-distributed-cre...

Any suggestions of what might be worth $150,000 in all of this?

At a basic end, this seems to be similar to storing every other character of a suitable hash on two nodes (preferably running heterogeneous architectures). RSA's ability to 're-randomise' suggests the ability for the two machines to be able produce a plaintext version of the password, which obviously seems particularly dangerous, especially if somebody is sloppy and backs up both nodes to the same location.

Is there any distributed encryption algorithm that could be done that would allow straightforward credential verification as well as the ability to re-salt a hash securely without knowing the plaintext?
Knowing that you don't know how to correctly calculate the traffic required to reach a specific confidence for an A/B test makes you better than all those people who don't even know that they don't know, and just wing it.

(edit: remove multiple calculates!)
Another blog post full of useless advice based on an ignorant and oversimplified view of the world. Typical HN garbage.
Gurtam took part in M2M Partner Event 2012
I want to try it, but it looks uncomfortable.
What browsers support this?

Chrome 23.0.1271.22 on OS X and it doesn't seem to be supported.
I never much cared for UT3 on the service (maybe it was the game, maybe it was the connection, but it felt sloppy) but Red Faction 3 was fantastic. That's a physics-based third person shooter/action title. I beat the whole game on OnLive.
2 "Unknown" JavaScript Resources
Cupcakes are business critical though. Oh wait, no, the other thing.
I'd rather see a kickstarter for a book on greenarrays programming :(
The difference between POST and PUT.Get it right!
They blew their budget on cupcakes.
This could get absurd very quickly if entire line-ups of products could get banned from almost a whole continent because of patents like slide to unlock.
Captain Crunch about phreaking and pranks played by Wozniak on Steve Jobs
I agree! But you won't do it forever, sooner or later you realize that you've worked in something you're not passionate about. It will result in serious consequences.

More important than passion and effort is long-term goals. I believe to be successful you must project yourself in the future. Look what you will be if you continue to walk the current path or what you will be if you change your path. The key is to choose the path that will bring you to a brighter future and stay in that path in turbulent times.

Choosing the right path is not as easy as speaking but an everyday exercice.
Which is a cop out anyway. Programmers don't get paid to "write code," they get paid to solve problems. Part of that is discussing options and strategies with teammates and making sure everyone is on the same page (or as close to the same page as possible when you have teammates with vastly disparate specialties and expertise).
Support right now is Chrome 23.0.1247.0+ (current Canary) and WebKit nightly.
Zerver - A new kind of webapp server
Do webdevelopers know or care about Cache-Control directive at all?
Sure it could, albeit in a more limited way. It has been done actually, at least in Flash (which includes some similar bitmap features, although it is vector based).

The main problem, as is with Flash based editors, would be performance.

>Is anyone aware of an article that explains the architecture of Photoshop? How pixels are processed through its stack of layers?

Well, the layers are just different images with alpha transparency drawn on top of each other, and the blend modes are just math done between two layers' pixel values.

Here's an (rather basic) article:

http://photoblogstop.com/photoshop/photoshop-blend-modes-exp...
To answer your question, yes.

Would ending software patents hinder Google's ability to compete effectively? I don't think so. Patents are not where the competitive action is.
3 Ways to Get 1 Bazillion "Likes" on Facebook
Connecting to SQL Server from Heroku with FreeTDS. Here is how on Cedar...
actually, i think the above is incorrect in detail, at least for some key distribution algorithms, but it gives the correct idea.
2012 has been an awesome year. UK based here so the Olympics were a high point (despite beforehand being fairly against the "waste" of money - i was wrong).

This is seriously cool.

I keep mixing up Eben Moglen and Elon Musk, am i alone?
Ruby-Javascript The javascript methodes you always wished you could have
Except usually Google's top results are exactly what I'm looking for. It's when they're not that those millions of results come in handy - otherwise there are tons of things I'd never find.
You Have to A-S-K if you Want to G-E-T
Interestingly this is more or less like the way I was taught linear algebra in high school.
I disagree because I find that it makes my code more elegant. A lot of smart developers I respect have also embraced early exits. But then again I haven't yet worked with large legacy codebases.

I'm still learning so I'd be grateful for a heads up if you make that blog post. I've put my email in my hn profile.
Very interesting, but the way they contrast French Montana and Drake / Wayne is a little misleading.

French is blowing up right now because of "Pop That", current #2 hip-hop single that features Rick Ross, Drake and Wayne.

Not trying to put French or Pandora down, but his JV deal with Maybach Music Group and the six figures that it usually costs to get the current top 2 rappers on his track probably have more to do with those royalties than Pandora right now.
Tesco Life vs Startup Life (Big Co. vs Small Co.)
This is true mostly for the (very) long distance trains. For local (not Mumbai local or elk) or maybe between two cities or so, the trains are quite late. Especially in North India, the part of the country I hail from.

It also has to do with punctuating the journey with many small stations and always being added halts.